4. The residuum, after filtering the alcoholic infusion, is to be weighed and examined. e. Distilled Tincture. 1. The alcoholic solution should be next distilled in a glass retort. 2. Observe whatever phenomena may occur during the distillation. 3. The result of the distillation should be tested with a. Distilled water. b. Prussiate of potash. c. Sulphate of iron. 4. Dry the residuum; weigh it, note its colour and consistency, and whether it attracts moisture. 5. Is it soluble in water? 6. Is it soluble in alcohol, æther, oil of turpentine, caustic, alkaline solution? 7 In either case, try the solution with the usual reagents. Description of Brooke's or Newman's Blow-pipe. By Mr. CHILDREN.* BROOKE'S, or Newman's Blow-pipe, although not calculated for mineralogical experiments, in others is highly useful. Indeed, when used with atmospheric air, it may be applied to all mineralogical purposes, though still with less advantage than the common blow-pipe in skilful hands. But when filled with a condensed mixture of oxygen and hodrogen gases in the proportion requisite to *From Berzelius on the Blow-pipe, translated from the French, by J. G. Children. form water, one essential character, the fusibility or infusibility of different substances as determined by the common blow-pipe, disappears before the intense heat produced by this, which levels all bodies to one general class of fusible substances; though very evident differences are still observable in the facility with which different bodies are reduced to the state of fusion. In return too for the character which is thus lost, we gain a new one in the appearance of the otherwise infusible body after it has been melted. This apparatus was first made at the desire of Mr. Brooke, by Mr. Newman of Lisle-street. An accident that occurred to Dr. Clarke, by the explosion of the reservoir, occasioned several attempts at its improvement. The most perfect of which is represented in Plate III. fig. 4. It was suggested by Mr. Professor Cumming, of Cambridge. a, fig. 1, is the reservoir made of sheet copper, 5 inches long, 3 inches wide, and 3 inches high; b, a syringe connected by a couple of stop-cocks, c, to the reservoir; d, is the head of the trough (or safety apparatus) fitting in its place by a screw, perfectly air tight: the trough is inserted in the reservoir in the direction of the dotted lines, and descends to the bottom: it is represented on a large scale at fig. 4; e, a stop-cock proceeding from the head d, and f, its jet fixed to it by the ball and socket, joint, g. When the instrument is used, its parts are to be put together as in fig 1, and the reservoir exhausted by working the piston of the syringe b. The stop-cocks must then be closed, the syringe with the upper stop-cock taken off, and the syringe alone placed in the upright position shewn at fig. 2. The bladder, h, containing the gases, must then be connected by the screw socket, k, and its stop-cock with the syringe. The syringe stop-cocks are now to be opened, when the gases will issue from the Description of Newman's Blow-pipe. 31 bladder, and fill the reservoir. The head of the trough is then to be unscrewed by the key, (fig. 3), and oil poured in, to about half an inch above the lower screen of wire gauze (see fig. 4.) and the head again screwed tight in its place. The gases are next to be condensed into the reservoir, by working the piston of the syringe as before, and all the stop-cocks being now shut, the apparatus is ready for use. During the whole time the jet is burning, the oil will be heard to play in the trough. If the current be inflamed, and the instrument abandoned to itself, the jet will go on burning until the expansive force of the atmosphere within the box is no longer sufficient to propel a stream with the required rapidity through the tube; at this time the inflammation will pass backwards, unless the tube be very fine, and will fire the small quantity of mixture in the upper part of the trough, and then its effects will cease, the atmosphere in the reservoir remaining as before. When, however, the regular use of the instru ment is required, it is better to shut the jet-cock before the atmosphere is quite out, and condense in a fresh portion of gas. Attention should be paid to the quantity of oil in the trough: it should cover the gauze, but not to too great a height; if there be too much oil, it is possible that the agitation caused by the passage of the gas through it, may throw a drop or two through the gauze above, against the inner orifice of the jet tube, which would cause a sputtering in the flame. The oil should be emptied out from the trough when the apparatus is laid by. Fig. 4 is a section of the trough and part of the reservoir drawn, on a large scale, in order to render its construction more distinct. |